All the martyrs in the history of the world are not sufficient to establish the correctness of an opinion. Martyrdom, as a rule, establishes the sincerity of the martyr, — never the correctness of his thought. Things are true or false in themselves. Truth cannot be affected by opinions; it cannot be changed, established, or affected by martyrdom. An error cannot be believed sincerely enough to make it a truth.

Robert Green Ingersoll (1833–1899) American lawyer, freethinker, orator

Lecture (1881-05-01) “The Great Infidels,” Booth’s Theater, New York
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See also Colton (1820), Schnitzler (1927).